1. Field of the Invention
The invention relates to a battery module detecting device and a battery module detecting method, and more particularly, to a detecting device and a detecting method of measuring the resistance of the connecting device instantly when the battery module is used, so that the resistance can be an assembly quality indicator of the battery module.
2. Description of the Prior Art
A battery is a device of converting the energy generated by the chemical reaction into the electrical energy. A single battery unit can only provide a fixed range of voltage depending on the types of its chemical reactions. Therefore, in order to provide a power source of higher voltage or other specific voltage, in practical applications, several battery units are usually connected serially or in parallel to be a battery module, and then the power is outputted.
A battery module formed by several battery units connected serially or in parallel. The quality of the battery module depends on not only the quality of the battery units, but also the connection arts between the battery units. In order to obtain the battery module having better quality, the battery units having better quality can be selected in advance to form the battery module. And, the quality of the connection arts between the battery units depends on the skills of assembling and designing the connecting mechanisms between different battery units.
In the battery module, the connection between two battery units is achieved by electrically connecting two electrodes having different polarities on different battery units respectively. In detail, the two electrodes can be directly contacted, or connected by a metal rod or wire. If the electrodes are directly contacted, it will be inconvenient for disposing, using, or inspection and maintenance. Therefore, in practical applications, it is common that the battery units are firstly arranged side by side to make the electrodes at the same side, and then the metal connecting rod is used to connect the electrodes.
If the metal connecting rod is used to connect the electrodes, the problem that the conduction quality is hard to be controlled must be taken into consideration. More detail, the conditions of oxidation or loosing may be occurred on the contacting points or surfaces between the metal connecting rod and the electrodes of the battery units to cause the increasing of the resistance. In this condition, if the battery module is continued to be used, the temperature of the loosed contacting points or surfaces will be high to cause the fire on the circuit or other electronic hazards.
In general, the metal connecting rod is locked on the electrode of the battery unit through the screw; therefore, the assembling quality between the battery units conventionally depends on the locking torque of assembling screw. The larger locking torque of assembling screw usually means firmer locking condition to prevent the increasing of the resistance caused by the shrinking of the contacting area, and the opportunity that the contacting surface of the metal connecting rod and the electrodes can be also reduced to lower the possibility of resistance increased caused by the oxidation of the contacting surface.
Since the tiding degree of the screw used to lock the metal connecting rod and electrodes may be changed with time, therefore, the locking quality of the screw must be usually tested to make sure the assembling quality and the using safety of the battery module. However, the locking torque of the screw must be measured under the condition that the battery module is not powered, so that the hazards of an electric shock and a short of the circuit will be prevented. Based on the above-mentioned limitations, it is hard to monitor the assembling quality of the battery module on time when the battery module is used.
On the other hand, during the assembling process, there will be some unclean substances (e.g., verdigris or electrolyte) on the surfaces of the metal connecting rod and electrodes to cause the increasing of the contact resistance between the metal connecting rod and electrodes to make the battery module become failure. However, it is hard to measure this variation of resistance by an ordinary low ohmmeter. In detail, the ordinary low ohmmeter is used to measure the resistance of the passive components (e.g., the cable), and its measuring arrange is higher than the milli-ohm level. However, the measuring range of the contacting resistance between the electrodes of the battery and the connecting rod is usually lower than the milli-ohm level. Therefore, it is hard to use the ordinary low ohmmeter to measure the variation of the contacting resistance between the metal connecting rod and electrodes. In addition, the ordinary low ohmmeter is not designed to perform the resistance measurement under the condition that the metal is conducted. Therefore, if the contacting resistance between the metal connecting rod and the electrodes is measured when the battery is powered, it may be very dangerous to use.
As mentioned above, the variation of the resistance can not be measured by the low ohmmeter when the battery is powered, and the locking torque variation of the screw can not show the variation of the resistance. Therefore, in practical applications, the locking torque variation of the screw fails to be an ideal quantitative indicator to represent the assembling quality of the battery module, and it also lacks other effective methods to monitor the assembling quality of the battery module instantly.